Systems and methods for attaching a prosthesis within a body lumen or hollow organ

ABSTRACT

Systems and methods introduce and deploy prosthesis into a blood vessel or hollow body organ by intra-vascular access. The prosthesis is secured in place by fasteners which are implanted by an applier that is also deployed by intra-vascular access. The applier is configured to permit controlled, selective release of the fastener in a step that is independent of the step of implantation.

RELATED APPLICATIONS

This application is a Division of and claims the benefit of U.S. patentapplication Ser. No. 14/210,683, filed Mar. 14, 2014, now allowed, whichis a Continuation of U.S. patent application Ser. No. 13/495,836, filedJun. 13, 2012, now U.S. Pat. No. 8,685,044 which is a Continuation ofU.S. patent application Ser. No. 10/786,465, filed Feb. 25, 2004, nowU.S. Pat. No. 8,231,639, which is a Continuation-in-Part of U.S. patentapplication Ser. No. 10/693,255, filed Oct. 24, 2003, now U.S. Pat. No.6,929,661, which claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/489,011, filed Jul. 21, 2003. U.S. patentapplication Ser. No. 10/786,465 now issued as U.S. Pat. No. 8,231,639,is also a Continuation-in-Part of U.S. patent application Ser. No.10/307,226, filed Nov. 29, 2002, now issued as U.S. Pat. No. 8,075,570,which is a Continuation-in-Part of U.S. patent application Ser. No.10/271,334, filed Oct. 15, 2002, now issued as U.S. Pat. No. 6,960,217,which claims the benefit of U.S. Provisional Patent Application Ser. No.60/333,937, filed Nov. 28, 2001. The disclosures of which are hereinincorporated by reference in their entirety.

FIELD OF INVENTION

The invention relates generally to prostheses, and in particular, theattachment of prostheses used in the repair of diseased and/or damagedsections of a hollow body organ and/or a blood vessel.

BACKGROUND OF THE INVENTION

The weakening of a vessel wall from damage or disease can lead to vesseldilatation and the formation of an aneurysm. Left untreated, an aneurysmcan grow in size and may eventually rupture.

For example, aneurysms of the aorta primarily occur in abdominal region,usually in the intrarenal area between the renal arteries and the aorticbifurcation. Aneurysms can also occur in the thoracic region between theaortic arch and renal arteries. The rupture of an aortic aneurysmresults in massive hemorrhaging and has a high rate of mortality.

Open surgical replacement of a diseased or damaged section of vessel caneliminate the risk of vessel rupture. In this procedure, the diseased ordamaged section of vessel is removed and a prosthetic graft, made eitherin a straight of bifurcated configuration, is installed and thenpermanently attached and sealed to the ends of the native vessel bysuture. The prosthetic grafts for these procedures are usuallyunsupported woven tubes and are typically made from polyester, ePTFE orother suitable materials. The grafts are longitudinally unsupported sothey can accommodate changes in the morphology of the aneurysm andnative vessel. However, these procedures require a large surgicalincision and have a high rate of morbidity and mortality. In addition,many patients are unsuitable for this type of major surgery due to otherco-morbidities.

Endovascular aneurysm repair has been introduced to overcome theproblems associated with open surgical repair. The aneurysm is bridgedwith a vascular prosthesis, which is placed intraluminally. Typicallythese prosthetic grafts for aortic aneurysms are delivered collapsed ona catheter through the femoral artery. These grafts are usually designedwith a fabric material attached to a metallic scaffolding (stent)structure which expands or is expanded to contact the internal diameterof the vessel. Unlike open surgical aneurysm repair, intraluminallydeployed grafts are not sutured to the native vessel, but rely on eitherbarbs extending from the stent, which penetrate into the native vesselduring deployment, or the radial expansion force of the stent itself isutilized to hold the graft in position. These graft attachment means donot provide the same level of attachment when compared to suture and candamage the native vessel upon deployment.

SUMMARY OF THE INVENTION

The invention provides apparatus, tools, systems, and methods forrepairing diseased and/or damaged sections of a hollow body organ and/ora blood vessel. The apparatus, tools, systems, and methods find use,e.g., in the introduction and deployment of a prosthesis into a bloodvessel or hollow body organ, which desirably is achieved byintra-vascular access. The prosthesis is secured in place by fasteners,which are implanted by the apparatus, tools, systems, and methods thatembody one or more features of the invention, which are also desirablydeployed by intra-vascular access.

According to one aspect of the invention, the applier is configured topermit controlled, selective release of the fastener in a step that isindependent of the step of implantation. According to one embodiment ofthis aspect of the invention, the applier includes a driven member thatis carried on a tool body. The tool body can include, e.g., a tube, suchas a catheter, to permit intra-vascular deployment of the driven member.The driven member is operable to apply an implantation force to thefastener. A drive actuator operates the driven member. The applier alsoincludes a fastener-engaging mechanism on the driven member. Themechanism is operable in a first condition to couple the fastener to thedriven member to transfer the implantation force from the driven memberto the fastener. Implantation of the fastener can thereby be achieved.The mechanism is also operable in a second condition to release thefastener from the driven member. According to this aspect of theinvention, the mechanism includes a second actuator, which places themechanism in the second condition, to release the fastener. The secondactuator is operable independent of the drive actuator. There can thusbe a definite, stepwise separation between implanting the fastener intissue using the implantation tool and releasing the fastener from theimplantation tool after implantation is satisfactorily achieved.

Another aspect of the invention provides a tool that can be used toapply an implantation force to a fastener, which is sized and configuredfor implantation in tissue in response to an implantation force appliedaccording to prescribed conditions. The tool is coupled to a controller,which interrupts implantation before it is completed, and interjects a“go”/“no go” decision-making step before proceeding further. The toolincludes a driven member carried on a tool body. The tool body cancomprise, e.g., a tube, such as a catheter. The driven member isoperable to apply the implantation force. A mechanism on the drivenmember couples the fastener to the driven member to transfer theimplantation force from the driven member to the fastener. According tothis aspect of the invention, a controller is coupled to the drivenmember. The controller executes differing operational phases during theimplantation process. During an initial phase the driven member isoperated to apply the implantation force under conditions that do notachieve the prescribed conditions, so that only partial implantation ofthe fastener occurs. A lull phase commences at the end of the initialphase. The lull phase interrupts operation of the driven member. Thereis a final phase, which operates the driven member under conditions thatsupplement the conditions of the initial phase to achieve the prescribedconditions, and thus achieve complete implantation. However, thecontroller requires, after the initial phase, a prescribed command toadvance from the lull phase to the final phase. The lull phase requiresa decision be made before implantation of the fastener is finalized. Ifimplantation during the initial phase is deemed not to be satisfactory,implantation can be aborted, and the fastener (now only partiallyimplanted) can be withdrawn. The decision can comprise a consciousdecision by the operator and/or a decision based, at least in part, uponphysical or operational conditions sensed during the initial phase.

Another aspect of the invention provides a tool for applying animplantation force to a fastener that is sized and configured forimplantation in tissue in response to an implantation force. The toolcomprises a driven member carried on a tool body that is operable toapply the implantation force. According to this aspect of the invention,an element is included that tethers the fastener to the tool body. Thetethering element safeguards against inadvertent loss of the fastenerprior to implantation. The tethering element includes a frangibleportion, so that, once the fastener is satisfactorily implanted, thetethering element can be parted from the fastener and the tool bodyremoved.

The invention also provides various systems and methods for using theabove-described devices to implant tissue in a vessel or hollow bodyorgan.

Other features and advantages of the invention shall be apparent basedupon the accompanying description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be understood from the following detailed descriptionof preferred embodiments, taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a perspective view of a prosthesis having a fastening regionthat accommodate s the introduction of one or more fasteners.

FIG. 2 is a perspective view of the prosthesis shown in FIG. 1, showingthe attachment of fasteners in the fastening region.

FIG. 3 is a perspective view of the prosthesis shown in FIG. 1positioned within an abdominal aortic aneurysm.

FIG. 4 is a perspective view of the prosthesis shown in FIG. 3 as it isbeing deployed by an intra-vascular catheter.

FIG. 5 is a perspective view of the prosthesis shown in FIG. 3 after itbeen deployed and as fasteners are being implanted by an intra-vascularfastener applier.

FIG. 6 is a side view, partly broken away and in section, of anintra-vascular fastener applier that can be used to implant fasteners inthe prosthesis shown in FIGS. 1 and 2, in the manner shown in FIG. 5.

FIG. 7 is a perspective view of a type of helical fastener that can beimplanted using the intra-vascular fastener applier shown in FIG. 6.

FIG. 8A(1) is an enlarged view of a carrier for implanting a fastener ofthe type shown in FIG. 7, the carrier being located at the distal end ofan intra-vascular fastener applier of the type shown in FIG. 8A(2), thecarrier being shown in a condition to receive a fastener prior toimplantation.

FIG. 8A(2) is a side view, partly broken away and in section, of afastener applier that includes, at its distal end, a carrier as shown inFIG. 8A(1), the carrier being shown after receipt of a fastener and asthe carrier is being rotated to implant the fastener in aprosthesis/tissue wall.

FIG. 8B(1) is an enlarged view of the carrier shown in FIG. 8A(1), thecarrier being shown in a condition to release a fastener afterimplantation.

FIG. 8B(2) is a side view, partly broken away and in section, of thefastener applier that includes, at its distal end, the carrier shown inFIG. 8B(1), the carrier being shown releasing a fastener following itsimplantation in a prosthesis/tissue wall.

FIG. 8C is a side view, partly broken away and in section, of thefastener applier shown in FIG. 8A(2), the carrier being shownwithdrawing or retrieving a fastener from a prosthesis/tissue wall.

FIG. 9A(1) is an enlarged view of another embodiment of a carrier fromimplanting a fastener of the type shown in FIG. 7, the carrier beinglocated at the distal end of an intra-vascular fastener applier of thetype shown in FIG. 9A(2), the carrier being shown in a condition toreceive a fastener prior to implantation.

FIG. 9A(2) is a side view, partly broken away and in section, of afastener applier that includes, at its distal end, a carrier as shown inFIG. 9A(1), the carrier being shown after receipt of a fastener and asthe carrier is being rotated to implant the fastener in aprosthesis/tissue wall.

FIG. 9B(1) is an enlarged view of the carrier shown in FIG. 9A(1), thecarrier being shown in a condition to release a fastener afterimplantation.

FIG. 9B(2) is a side view, partly broken away and in section of thefastener applier that includes, at its distal end, the carrier shown inFIG. 9B(1), the carrier being shown releasing a fastener following itsimplantation in a prosthesis/tissue wall.

FIG. 10A(1) is an enlarged view of a carrier for implanting a fastenerof the type shown in FIG. 7, the carrier being located at the distal endof an intra-vascular fastener applier of the type shown in FIG. 10A(2),the carrier being shown in a condition to receive a fastener prior toimplantation.

FIG. 10A(2) is a side view, partly broken away and in section, of afastener applier that includes, at its distal end, a carrier as shown inFIG. 10A(1), the carrier being shown after receipt of a fastener and asthe carrier is being rotated to implant the fastener in aprosthesis/tissue wall.

FIG. 10B(1) is an enlarged view of the carrier shown in FIG. 10A(1), thecarrier being shown in a condition to release a fastener afterimplantation.

FIG. 10B(2) is a side view, partly broken away and in section, of thefastener applier that includes, at its distal end, the carrier shown inFIG. 10B(1), the carrier being shown releasing a fastener following itsimplantation in a prosthesis/tissue wall.

FIG. 11 is an enlarged view of a carrier for implanting a fastener ofthe type shown in FIG. 7, the carrier being located at the distal end ofan intra-vascular fastener applier of the type shown in FIGS. 10A(2) and106(2), the carrier being shown in a condition to receive a fastenerprior to implantation.

FIGS. 12A and 12B are perspective views of a fastener assemblycomprising a helical fastener and a cap, FIG. 12A showing an explodedview of the assembly and FIG. 12B showing an assembled view of theassembly.

FIGS. 13A and 13B are side views showing in interior of a carrier forimplanting a fastener assembly of the type shown in FIG. 12B, thecarrier being located at the distal end of an intra-vascular fastenerapplier of the type shown in FIG. 15A, the carrier in FIG. 13A beingshown in a condition to receive the fastener assembly prior toimplantation, the carrier in FIG. 13B being shown in a condition torelease the fastener assembly after implantation.

FIGS. 14A and 14B are side views showing the mounting of the fastenerassembly shown in FIG. 12B to the carrier shown in FIG. 13A.

FIG. 15A is a side view, partly broken away and in section, of afastener applier that includes, at its distal end, a carrier as shown inFIG. 13A, the carrier being shown after receipt of a fastener assemblyas shown in FIG. 14B and as the carrier is being rotated to implant thefastener assembly in a prosthesis/tissue wall.

FIG. 15B is a side view, partly broken away and in section, of afastener applier shown in FIG. 15A, the carrier being shown releasingthe fastener assembly after its implantation in a prosthesis/tissuewall.

FIG. 15C is a side view, partly broken away and in section, of afastener applier shown in FIG. 15A, the carrier being shown withdrawingor retrieving the fastener assembly from a prosthesis/tissue wall.

FIG. 16A(1) is an enlarged view of a carrier for implanting a fastenerof the type shown in FIG. 7, the carrier being located at the distal endof an intra-vascular fastener applier of the type shown in FIG. 16A(2),the carrier being shown holding a fastener prior to implantation.

FIG. 16A(2) is a side view, partly broken away and in section, of afastener applier that includes, at its distal end, a carrier as shown inFIG. 16A(1), the carrier being rotated to implant the fastener in aprosthesis/tissue wall.

FIG. 16B is a side view, partly broken away and in section, of thefastener applier shown in FIG. 16A(2), the carrier being shown at theend of a first operating phase, during which the fastener has beenpartially implanted in a prosthesis/tissue wall and in which thefastener remains secured to the carrier.

FIG. 16C is a side view, partly broken away and in section, of thefastener applier shown in FIG. 16A(2), the carrier being shown followingthe first operating phase and at the end of a second operating phase,during which the fastener has been fully implanted and released from thecarrier into a prosthesis/tissue wall.

FIG. 16D is a side view, partly broken away and in section, of thefastener applier shown in FIG. 16A(2), the carrier being shown followingthe first operating phase and during another operating phase, duringwhich the fastener is being withdrawn or retrieved from aprosthesis/tissue wall while still secured to the carrier.

FIGS. 17A and 17B are side views of a fastener applier of the type shownin any of the preceding figures, the fastener applier including anelement releasably tethering a fastener to the fastener applier, FIG.17A showing the tethering element holding on to the fastener followingits implantation in a prosthesis/tissue wall, and FIG. 17B showing thetethering element after having been parted from the fastener.

FIGS. 18A and 18B show an embodiment of a tethering element of the typeshown in FIGS. 17A and 17B, the tethering element being secure to afrangible portion of the fastener, FIG. 18A showing the tetheringelement holding on to the fastener following its implantation in aprosthesis/tissue wall, and FIG. 18B showing the tethering element afterhaving been parted from the fastener.

FIG. 19A shows an embodiment of a tethering element of the type shown inFIGS. 17A and 17B, the tethering element being secured to a frangiblejoint that is broken by rotating the tethering element relative to thefastener.

FIG. 19B shows an embodiment of a tethering element of the type shown inFIGS. 17A and 17B, the tethering element being secured to a frangiblejoint that is broken by pulling the tethering element from the fastener.

FIGS. 20A and 20B show an embodiment of a tethering element of the typeshown in FIGS. 17A and 17B, the tethering element being secured to ascrew joint (FIG. 20A) that is parted by rotating the tethering elementrelative to the fastener (FIG. 20B).

FIGS. 21A and 21B show an embodiment of a tethering element of the typeshown in FIGS. 17A and 17B, the tethering element being secured to aball joint (FIG. 21A) that is parted by pulling the tethering elementaway from the fastener (FIG. 21B).

FIGS. 22A and 22B show an embodiment of a tethering element of the typeshown in FIGS. 17A and 17B, the tethering element being secured to aslip joint (FIG. 22A) that is parted by pulling the tethering elementaway from the fastener (FIG. 22B).

FIGS. 23A and 23B show an embodiment of a tethering element of the typeshown in FIGS. 17A and 17B, the tethering element being secured to aknotted joint (FIG. 23A) that is parted by pulling the tethering elementaway from the fastener (FIG. 23B).

FIGS. 24A and 24B show an embodiment of a tethering element of the typeshown in FIGS. 17A and 17B, the tethering element being secured to afrangible tube joint (FIG. 24A) that is parted by pulling a rip cord(FIG. 24B).

FIGS. 25A and 25B show an embodiment of a tethering element of the typeshown in FIGS. 17A and 17B, the tethering element including aninterlocking mechanism.

DETAILED DESCRIPTION OF THE INVENTION

I. Prosthesis

A. Structure

FIG. 1 shows a prosthesis 10. The prosthesis 10 serves to repair orreinforce a region of a vessel wall or hollow body organ which has beenweakened by disease or damage.

In the illustrated embodiment (see FIG. 1), the prosthesis 10 comprisesa tubular trunk 12. The trunk 12 is sized and configured to fit within atargeted region of a hollow body organ and/or a blood vessel. Thetargeted region is selected on the basis of certain anatomiccharacteristics. These characteristics include a weakened conditionedcaused, e.g., by disease or damage.

The trunk 12 forms a generally cylindrical structure with an openinterior lumen 19. In the illustrated embodiment, the trunk 12 includesa prosthetic material 14 supported by a scaffold 16. The prostheticmaterial 14 is selected on the basis of its biocompatibility,durability, and flexible mechanical properties. The material 14 cancomprise, e.g., woven polyester or ePTFE.

The scaffold 16 is desirable sized and configured to permit non-invasivedeployment of the prosthesis 10 by an intra-vascular catheter. With thiscriteria in mind, the scaffold 16 is sized and configured to assume acompressed or collapsed, low profile condition, to permit itsintra-vascular introduction into the hollow body organ and/or bloodvessel by a catheter, as will be described in greater detail later.

Also with this criteria in mind, the scaffold 16 is sized and configuredfor expansion in situ from its collapsed condition into an expandedcondition in contact with tissue in the targeted region, as will also bedescribed in greater detail later.

In this respect, the scaffold 16 can comprise, e.g., a malleable plasticor metal material that expands in the presence of an applied force. Inthis arrangement, the deployment catheter can include, e.g., anexpandable body, such as a balloon, to apply the expansion force to thescaffold 16 in situ.

Alternatively, the scaffold 16 can comprise a self-expanding plastic ormetal material that can be compressed in the presence of a force, butself-expands upon removal of the compressive force. In this arrangement,the deployment catheter can include, e.g., a sleeve that can bemanipulated to enclosed the scaffold 16 in a collapsed condition,thereby applying the compressive force, and to release the scaffold 16when desired to allow the scaffold 16 to self-expand in situ.

For self-expansion, the scaffold 16 can include individualself-expanding, zigzag type main stent rings 22. The main stent rings 22can be made, e.g., from Nitinol® wire. Still, other materials,manufacturing methods and designs can be used.

The main stent rings 22 need not be attached to one another throughoutthe prosthesis material 14, as FIG. 1 shows. The individual main stentrings 22 allow for longitudinal compliance while maintaining radialsupport of the open interior lumen 18. This technical feature allows theprosthesis 10 to more readily accommodate changes in morphology in thetargeted region. Still, it may be desirable in certain locations withinthe prosthesis structure to have attachments between the individual mainstent rings 22 to provide enhanced stability and/or additional radialsupport.

Each of the main stent rings 22 can be, e.g., sewn onto prostheticmaterial 14. In the illustrated embodiment, in which the prostheticmaterial 14 is woven polyester, the attachment of the main stent rings22 can be made, e.g., with polyester suture.

However, it is also contemplated that other attachment means could beutilized to secure the main stent rings 22 to the prosthetic material14. These means include bonding; capturing the main stent rings 22between two layers of prosthetic material 14; and incorporating the mainstent rings 22 directly into the prosthetic material 14.

In certain locations, it is desired to have the main stent rings 22attached to the outer diameter of the prosthetic material 14. Still, itis also contemplated that the main stent rings 22 could be attached tothe inner diameter of the prosthetic material 22.

At least one end of the trunk 12 desirably also includes one or more endstent rings 24. The principal purpose of an end stent ring 24 is toprovide a seal between the trunk 12 and adjoining tissue. This sealingfunction is particularly desirable when the prosthesis 10 is deployed ina blood vessel or other body organ, where body fluids are intended toreside or pass through the prosthesis 10. The end sent rings 24 can alsoserve, with the main stent rings 22, to help maintain the position ofthe prosthesis 10 in the targeted region.

The trunk 12 (material 14 and/or scaffold 16) can carry radiopaquemarkers 46 to help fluoroscopically position the prosthesis 10. Themarkers 46 can take the form, e.g., of marker bands, tight wound coils,or wire made from radiopaque material such as platinum,platinum/iridium, or gold.

The trunk 12 also desirably includes at least on fastening region 26that accommodates the introduction of one or more fasteners 28 to anchorthe prosthesis 10 in place (see FIG. 2). It is desirable that thisregion 26 of the trunk 12 be specially sized and configured for thereceipt and retention of fasteners 28. For example, the size and spacingof ring stent patterns can be configured in the region 26 to speciallyaccommodate the placement of fasteners; and/or woven fibers with an“X-pattern” or a “sinusoidal pattern” can be used in the region 26 tospecially accommodate placement of fasteners; and/or the prostheticmaterial 14 can be folded-over to form multiple layers, to reinforce theprosthesis in the region 26 where fasteners are placed; and/or denserweave patterns or stronger fibers can be used, selected from, e.g.,Kevlar™ material or Vectran™ material or metallic wire woven alone orinterwoven with typical polyester fibers in the region 26 were fastenersare placed. It may also be desirable to fluoroscopically indicated thisregion 26 with auxiliary radiopaque markers 30 on the prostheticmaterial 14, and/or auxiliary stent rings 32 to aid in positioning thefasteners.

The fasteners 28 can be variously constructed. They can, e.g., comprisehelical fasteners or staples.

Desirably, like the prosthesis 10 itself, the fasteners 28 areintroduced by an intra-vascular fastener attachment assembly. Details ofvarious fastener attachment assemblies will be described in greaterdetail later.

B. Use of the Prosthesis

The targeted region for deployment of the tissue reinforcementprosthesis 10 as just described can vary. In FIG. 3, the trunk 12 issized and configured to extend, for purposes of illustration, in theaorta adjacent the renal arteries distally to a location proximal thenatural bifurcation of the iliac arteries. However, this targeted siteof deployment is selected for purposes of illustrating the features ofthe prosthesis 10, and it is not intended to be limiting.

As shown in FIG. 3, the fastening region 26 is located in the neck ofthe aorta adjacent to the renal arteries. The features of the fasteningregion 26, previously described, make possible the secure attachment ofthe prosthesis 10, without migration.

In this arrangement (see FIG. 3), the trunk 12 may include a supra-renalstent 44 at its proximal end, which extends beyond the prostheticmaterial 14. When deployed within the aorta, this stent 44 would extendabove the level of the renal arteries, as FIG. 3 shows. The supra-renalstent 44 orients the prosthesis 10 within the lumen and aids inmaintaining the position of the prosthesis 10 in the aorta withoutobstructing the normal blood flow into the renal arteries.

During use (see FIGS. 4 and 5), a first catheter 20 is navigated over aguide wire 48 through an iliac to the desired location within the aortanear the renal arteries. The catheter 20 carries the prosthesis 10 in aradially reduced configuration. At the targeted site, the catheter 20releases the prosthesis 10, which expands radially into the positionshown in FIG. 5.

A fastener assembly 34 is next deployed (which is shown generally inFIG. 5) to place fasteners 28 into the fastening region 26 of the trunk12. The prosthesis 10 is thereby secured in position.

II. Prosthesis Attachment Systems and Methods

The fastener assembly 34 can be variously constructed and configured.

In an illustrated arrangement (see FIG. 6), the fastener attachmentassembly 34 comprises a fastener guide component 36 and a fastenerapplier component 38. The guide component 36 can comprise, e.g., a guidesheath that desirably has a steerable or deflectable distal tip. Theguide component 36 can be initially deployed over the guidewire that isused to deliver and position the prosthesis 10. The guide wire can bewithdrawn after the guide component 36 is deployed and positioned, sothat the applier component 38 can be introduced.

In this arrangement, the applier component 38 is desirably deployedthrough the guide component 36. A fastener drive mechanism 40 n thefastener applier component 38 carries at least one fastener 28. Thefastener drive mechanism 40 advances the fastener 28, causing it topenetrate the prosthesis 10 and underlying tissue wall. In this way, thefastener anchors the prosthesis 10 firmly in place.

In the illustrated embodiment (see FIG. 6), the fastener applier 38comprises a catheter 42. The catheter 42 carries the fastener drivemechanism 40 at its distal tip.

The fastener drive mechanism 40 comprises carrier 50. The carrier 50 issized and configured to carry a selected fastener 28. The fastener drivemechanism 40 also includes a driver 52, which is coupled to impartmovement to the carrier 50. The driver 52 and carrier 50 can comprise anintegrated unit, with the carrier 50 being formed on the distal end ofthe driver 52, as shown, or they can comprise separate components, e.g.,with the driver comprising a clutch or the like for the carrier 50. Thedriven movement deploys the fastener 28. The type of driven movementthat is imparted depends upon the type of fastener 28 that is used.

In the illustrated embodiment (see FIG. 7) the fastener 28 comprises isan open helical coil 54 with a sharpened leading tip 56. This type ofhelical fastener is deployed into tissue by rotational movement.Consequently, rotational movement is imparted by the driver 52 to thecarrier 50, which is sized and configured to carry the fastener shown inFIG. 7.

The actuation of the driver 52 can, of course, be accomplished invarious ways, e.g., mechanical (i.e., manual or hand-powered),electrical, hydraulic, or pneumatic.

In the illustrated embodiment (see FIG. 6), a drive motor 58 impartsrotation to the driver 52 through a drive cable 60. In the illustratedembodiment (FIG. 6), the drive motor 58 is housed in a handle 62, whichis carried at the proximal end of the catheter 42. The drive cable 60extends from the handle 62, through the catheter 42, and couples to thedriver 52 at the distal end of the catheter 42. The drive cable 60 isdesirably made of a suitable material that allows for both bending androtation.

Activation of the drive motor 58 (e.g., by a physician controlled switch64 on the handle 62) rotates, as a unit, the drive shaft 60, the driver52, the carrier 50, and the fastener 28 in the carrier 50. Therotational movement causes the helical fastener 28 to travel into theprosthesis 10 and the tissue wall.

The implantation force of the fastener drive mechanism 40 is desirablyresolved in some manner to provide positional stability and resistunintended movement of the carrier 50 relative to the implantation site.A resolution force is desirably applied to counteract and/or oppose theimplantation force of the fastener drive mechanism 40. It is desirableto resolve some or all or a substantial portion of the implantationforce within the vessel lumen (or other hollow body organ) itself, andpreferably as close to the implantation site as possible.

The tubular body of the guide component 36 and/or the shaft of thecatheter 42 can be sized and configured to possess sufficient columnstrength to resolve some or all or at least a portion of theimplantation force within the vessel lumen or hollow body organ. FIG. 5shows the guide component 36 braced against the vessel wall to apply acounterbalancing resolution force. In addition, or alternatively, theguide component 36 and/or the fastener applier component 38 can includesome form of stabilization means for applying a counteractive force ator near the carrier 50. Various types of stabilization means aredisclosed in co-pending U.S. patent application Ser. No. 10/669,881,filed Sep. 24, 2003, and entitled “Catheter-Based Fastener ImplantationApparatus and Methods with Implantation Force Resolution.”

The carrier 50 itself can be carious constructed, as can the fastener 28to facilitate its coupling to the carrier 50. Representative embodimentswill now be described.

A. Carriers with Independent Fastener Release Mechanisms

1. Carriers with Fastener Support Elements Having Release Mechanisms

The proximal end of the fastener 28 desirably includes a fitting 66that, in use, couples the fastener 28 to the carrier 50. In oneillustrated embodiment (see FIG. 7), the fitting 66 comprises anL-shaped brace or leg 66. The L-shape leg 66 desirably bisects theentire interior diameter of the coil 54; that is, the L-shaped leg 66extends completely across the interior diameter of the coil 54, as FIG.7 shows.

In this arrangement, the carrier 50 is sized and configured to engagethe fitting 66, i.e., L-shaped leg 66, to thereby impart rotation to thehelical fastener 28 to achieve implantation. The L-shaped leg 66 alsoserves as a stop to prevent the helical fastener 28 from penetrating toofar into the tissue.

In one illustrated embodiment, the carrier 50 (see FIGS. 8A(1) and8A(2)) includes a fastener support element 68 that permits the selectiverelease of the fastener 28. The support element 68 has at least twooperating conditions.

In a first condition (see FIG. 8A(1)), the support element 68 engagesthe L-shaped leg 66 of the fastener 28 to hold the fastener 28 on thecarrier 50. In the first condition, rotation of the carrier 50 impartsrotation to the fastener 28 (as shown by the rotational arrow in FIG.8A(2), to allow implantation of the fastener 28 into the prosthesis10/tissues wall without releasing the fastener 28 (i.e., in response torotation in one direction, as FIG. 8A(2) shows), as well as allow thewithdrawal the fastener 28 from the prosthesis 10/tissue wall withoutreleasing the fastener 28 (i.e., in response to rotation in an oppositedirection, as FIG. 8C shows).

In a second condition (see FIGS. 8B(1) and 8(B)(2)), the support element68 releases the fastener 28. In the second condition, the fastener 28and the carrier 50 can be separated. Release of the fastener 28 from thecarrier 50 can be and desirably is accomplished without rotation of thecarrier 50. It is desirable that the support element 68 can affectseparation of the fastener 28 while the carrier 50 is stationary and notrotating.

The support element 68 therefore differentiates the step of operatingthe carrier 50 to implant the fastener 28 (by rotation of the carrier 59with the support element 68 in its first condition) from the step ofreleasing the fastener 28 from the carrier 50 (by placing the supportelement 68 in its second condition, which is desirably achievedindependent of rotation of the carrier 50). The support element 68thereby also makes possible the use of the carrier 50 to withdrawn thefastener 28 from tissue and to retrieve or reposition the fastener 28,if desired. Operation of the support element 68 independent of operationof the carrier 50 makes possible the release of the fastener 28 from thecarrier 50 in a separate releasing step, which can be delayed to assurethat implantation of the fastener 28 has been satisfactorily completed.

The features of the support element 68 just described can be achieved bythe use of various structural embodiments. In the embodiment shown inFIGS. 8A(1) and 8B(1), for example, the support element takes the formof hinged gripping jaws 70 on the distal end of the carrier 50. Thegripping jaws 70 are moveable between a mutually closed condition (i.e.,the first condition, as shown in FIG. 8A(1)) and a mutually openedcondition (i.e., the second condition, as shown in FIG. 8B(1)). TheL-shaped leg 66 of the fastener 28 is gripped by interference fit withina receptacle 72 formed between the jaws 70 when the jaws 70 are mutuallyclosed, as FIGS. 8A(1) and 8A(2) show. The receptacle 72 opens and freesthe L-shaped leg 66 when the gripping jaws 70 are mutually opened, asFIGS. 8B(1) and 8B(2) show.

In this embodiment, a physician-manipulated actuator 74 selectivelypivots the hinged gripping jaws 70 from their mutually closed conditionto their mutually opened condition. In the illustrated embodiment (seeFIGS. 8A(1) and 8B(1)), the actuator 74 comprises a pull cable 76 orstylet, which is coupled at its proximal end to a controller 78 on thehandle (see FIGS. 8A(2) and 8B(2)). The pull cable 76 extends throughthe catheter 42 and terminates at its distal end with a shaped camelement 78. The cam element 78 in the illustrated embodiment isball-shaped. It occupies the area defined between tapered, facing camsurfaces 80 formed on the interior of the gripping jaws 70, when thejaws 70 are mutually closed (FIG. 8A(1)), the cam element 78 rests inthe region of greatest distance between cam surfaces 80, adjacent thedistal end of the gripping jaws 70. In this arrangement, when thephysician manipulates the controller 78 to pull the cable 76 in an aftdirection (i.e., toward the handle 62) (FIG. 8B), the cam element 78travels on the tapered cam surfaces 80 toward the region of leastdistance between the surface 80. As it moves, the cam element 78 appliesforce against the cam surfaces 80 to pivot the jaws 70 open, i.e.,moving them from the mutually closed to the mutually opened condition,as FIG. 8B(1) shows.

In the illustrated embodiment, the hinged gripping jaws 70 are desirablybiased toward the mutually closed condition. A spring can be used forthe purpose. Desirably, the gripping jaws 70 are formed by machining ormolding from an elastic, spring-like material (metal or plastic). Theformed material includes an integral hinge 82, which normally biases thegripping jaws 70 closed. The hinge 82 yields to the force applied by thecam element 78 against the cam surfaces 80, but returns the jaws 70 totheir mutually closed condition in the absence of the force. In thisarrangement (see FIG. 8A(1)), a physician can snap fit the L-shaped leg66 of a fastener 28 into the receptacle 72 between the gripping jaws 70at time of use. The snap fir provides tactile assurance that thefastener 28 has been properly engaged within the receptacle 72 of thegripping jaws 70.

In an alternative embodiment (see FIGS. 9A(1) and 9B(1)), the supportelement 68 takes the form of spring-biased struts 84 on the carrier 50.The struts 84 resiliently open to accommodate snap-fit passage of theL-shaped leg 66 into a retaining space 87 between the struts 84,allowing the coil 54 of the fastener 28 to nest upon the struts 84 (asFIG. 9A(2) shows). The resilient, normally closed condition of thestruts 84 comprise the first operating condition, which holds thefastener 28 on the struts 84, thereby securing the fastener 28 to thecarrier 50. In this condition, rotation of the carrier 50 rotates thefastener 28, to allow implantation of the fastener 28 into tissue and/orwithdrawal of the fastener 28 from tissue.

In this arrangement, a physician-manipulated actuator comprising, e.g.,a push cable or stylet, can be advanced forward through the catheter byoperation of a controller 88 on the handle 62. The carrier 50 need notbe and desirably is not rotated during this operation. The push cable86, when advanced (see FIGS. 8B(1) and 8B(2), contacts the L-shaped leg66 and urges the leg 66 out of the retaining space 87 against theresiliently displaced by force of the L-shaped leg 66, which are causedto assume a temporary, mutually opened condition. The fastener 28 canthereby be ejected from the carrier 50.

In an alternative arrangement (see FIGS. 10A(1) and 10B(2)), the supportelement 68 may include normally open struts 90 that define a receptacle92 and include a detent 94 that governs passage of the L-shaped leg 66into and out of the receptacle 92. A physician-manipulated actuator 96comprising, e.g., a push-pull cable or stylet, can be advanced fore andaft through the catheter 42 into and out of contact with the detent 94,e.g., by operation of a controller 98 on the handle 62 (see FIGS. 10A(2)and 10(13)(2)). The cable 96, when advanced into contact with detent 94(see FIG. 10A(1) (1)) locks the detent 94 in a position projecting intothe receptacle 92. The detent 94, when locked, blocks entry into or outof the receptacle 92. The cable 96, when withdrawn from contact withdetent 94, unlocks the detent 94, and allows movement of the detent 94out of the position blocking the receptacle 92.

The detent 94, when unlocked (see FIGS. 10A(1) and 10A(2)), accommodatespassage of the L-shaped leg 66 into the retainer 92 between the struts90, while the remainder of the fastener 28 nests upon the struts 90. Thefastener 28 can be loaded onto the carrier 50 in this fashion. Thesubsequent locking of the detent 94 (see FIG. 10A(2)) blocks release ofthe L-shaped leg 66, securing the fastener 28 to the carrier 50. Thiscorresponds to the above-described first operating condition. In thiscondition, rotation of the carrier 50 rotates the fastener 28 (as shownby the rotational arrow in FIG. 10A(2)), to allow implantation of thefastener 28 into the prosthesis 10/tissue wall and/or withdrawal of thefastener 28 from the prosthesis 10/tissue wall.

The cable 96, when advanced out of the contact with detent 94, unlocksthe detent 94 (see FIGS. 10B(1) and 10B(2)). The carrier 50 need not beand desirable is not rotated during this operation. This allows passageof the L-shaped leg 66 past the detent 94 and free of the receptacle 92,as previously described, in response to aft movement of the catheter 42and attached carrier 50.

Alternatively, as shown in FIG. 11, the detent 94 may be biased by aspring 100 toward a normally projecting condition to serve the samefunction.

2. Carrier with Releasable Fastener Cap Assemblies

In another illustrated embodiment (sees FIGS. 12A and 12B), the fastener28 takes the form of a fastener cap assembly 102 that is releasablyfitted onto a specially adapted carrier 104 (see FIGS. 14A and 14B) attime of use. In the illustrated arrangement (see FIGS. 12A and 12B), thefastener cap assembly 102 includes a helical fastener 106 on which aproximal cap 108 is mounted. The cap 108 can comprise a plastic, metal,or ceramic biocompatible material. The cap 108 can be secured to theproximal end of the fastener 106, e.g., by adhesives, machining,molding, or welding. The cap 108 includes preformed side mounts 110. Inthis arrangement, the cap 108 serves the same general function as theL-shaped leg 66 shown in FIG. 7, i.e., it is a fitting secured to thefastener that enables the coupling of the fastener 28 to the carrier.

In this arrangement (see FIGS. 14A and 14B), the carrier 104 includes anattachment mechanism 112, which will be described in greater detaillater. The attachment mechanism 112 is sized and configured to engagethe mounts 110, to thereby couple the fastener assembly 102 to thecarrier 104 at time of use. The attachment mechanism 112 impartsrotation to the fastener assembly 102 when the carrier 104 is rotated(see FIG. 15A) to achieve implantation of the fastener assembly 102 intothe prosthesis 10/tissue wall without releasing the fastener assembly102 (i.e., in response to rotation of the carrier 104 in one direction,as FIG. 15A shows). The attachment mechanism 112 can also withdraw thefastener assembly 102 from the prosthesis 10/tissue wall (see FIG. 15C)without releasing the fastener assembly 102 (i.e., in response torotation of the carrier 104 in an opposite direction, as FIG. 15Cshows).

The carrier 104 also includes a release mechanism 114, as will bedescribed in greater detail later. The release mechanism 114 selectivelyreleases the fastener assembly 102 from the attachment mechanism 112(see FIG. 15B). Release of the fastener assembly 102 from the attachedmechanism 112 can be and desirably is accomplished without rotation ofthe carrier 104.

The carrier 104 with an attachment mechanism 112 to which a fastenerassembly 102 can be fitted at time of use, as well as an independent,selectively operable release mechanism 114 allows a physician to operatethe carrier 104 to implant the fastener assembly 102 separate from thestep of releasing the fastener assembly 102 after implantation has beenaccomplished. The carrier 104 with a selective release for the fastenerassembly 102 also makes possible the withdrawal the fastener assembly102 from tissue and the retrieval and/or reposition the fastenerassembly 104, if desired while the carrier 104 remains secured to thefastener assembly 102. In this arrangement, release of the fastenerassembly 102 from the carrier 104 can be accomplished once fastenerassembly 102 has been satisfactorily implanted, or otherwise at a timecontrolled by the operator.

The features of the carrier 104 as just described can be achieved by theuse of various structural embodiments. In the embodiment shown in FIGS.13A and 13B, the attached mechanism 1112 comprises a pair of gripperarms 116 coupled to the driver 52. The gripper arms 116 can be made bymachining or molding from a metal or plastic material. The gripper arms116 can be normally biased toward an inwardly deflected condition. Thebias can be achieved, e.g., by imparting a spring memory to the arms116. Alternatively, the arms 116 need not be biased inwardly, butinstead include outside edges that are inclined, as FIG. 13B shows. Thearms include outwardly projecting tabs 126 that are sized to snap intomounts 110 on the cap 108 (as FIG. 14B shows).

In this arrangement, the release mechanism 114 comprises a spacer rod118 extends between the gripper arms 116. The rod 118 carries at itsdistal end a cam element 120. When withdrawn from contact with thegripper arms 116 (as FIG. 13B shows), the gripper arms 116 arepositioned such that the tabs 126 will snap into the mounts 110 on thecap 108, see FIG. 14A shows. The cam element 120, when disposed incontact with the gripper arms 116 (as shown in FIG. 13A), spreads thegripper arms 116 (as shown in FIG. 13A), spreads the gripper arms 116apart, into an outwardly deflected condition, locking the tabs 116 intothe mounts 110, as FIG. 14B shows.

A spring 122 normally urges the cam element 120 toward contact with thegripper arms 116 (as shown in FIGS. 13A and 14B). The rod 118, whenpulled aft (as FIGS. 13B and 14A show) withdraws the cam element 120,and the gripper arms 116 are positioned to receive the cap 108. The rod118 extends through the catheter 42 and is coupled to a controller 124on the handle 62 (see FIGS. 15A and 15B).

When the gripper arms 116 are maintained by the cam element 120 in theiroutwardly deflected condition (see FIG. 14B), the tabs 126 lock into themounts 110 on the fastener cap 108, securing the fastener assembly 102to the carrier 104. Conversely, when the cam element 120 is withdrawn,the tabs 126 allow the fastener assembly 102 to be inserted onto orseparated from the carrier 104.

In use, the physician pulls back on the control 124 to withdraw the camelement 120 against the bias of the spring 122 and snap-fits a fastenerassembly 102 onto the carrier 104. The physician then releases thecontrol 124 to allow the spring 122 to return forward and lock thefastener assembly 102 onto the carrier 104. The physician then deploysthe catheter 42 holding the fastener assembly 102 to targeted site (seeFIG. 15A). By rotating the carrier 104, the physician implants thefastener assembly 102 into the prosthesis 10/tissue wall.

When the fastener assembly 102 has been satisfactorily implanted, thephysician pulls back on the control 124 and the catheter 42 (see FIG.15B) to separate the fastener assembly 102 from the carrier 104. Thephysician withdraws the catheter 42 and repeats the forgoing steps untilthe desired number of fastener assemblies 102 has been implanted.

Carriers with Two-Phase Ejection of Fasteners

The above-described embodiments a provide the ability to withdraw agiven fastener from a prosthesis/tissue wall prior to completion of theimplantation step. The above-described embodiments make this featurepossible by providing a fastener applier 38 that includes a fastenerrelease mechanism that works independent of the fastener implantationmechanism.

In FIGS. 16A(1)/A(2), 16B, and 16C, a fastener applier 38 includes afastener carrier 128 that implements this feature without an independentrelease mechanism. In FIGS. 16A(1)/A(2), 16B, and 16C, the fastenercarrier 128 is operated in two phases. The first or initial phaseadvances a fastener 28 into an incomplete implantation position within aprosthesis 10/tissue wall (FIG. 16B), which represents a sufficientdistance to gain purchase, but which is short of full implantation. Thatis, given that full implantation of the fastener 28 requires theapplication of an implantation force under prescribed conditions, i.e.,for a prescribed time period or for a prescribed number of rotations ofthe fastener 28 during the first phase under conditions that do notachieve the prescribed conditions. Thus, full implantation is notachieved. During the first phase, the fastener 28 remains coupled to thefastener carrier 128, to allow the physician to operate the fastenercarrier 128 to withdraw/retrieve the fastener 28, if desired (see FIG.16D).

The first phase presents a decision point to that physician. At end ofthe first phase, a lull phase exists, during which operation of thefastener carrier 128 is interrupted. A prescribed input command isrequired to move out of the lull phase. During the lull phase, thephysician can elect to withdraw or retrieve the fastener 28 (FIG. 16D).Alternatively, the physician can elect to continue implantation orproceed to the second phase. In the second or final phase, the fastenercarrier 128 advances the fastener 28 from the incomplete implantationposition (FIG. 16B) to the complete implantation position (FIG. 16C), atthe end of which the fastener 28 itself automatically separates from thefastener carrier 128. That is, during the second phase, implantationforce is applied to the fastener 28 under conditions that supplement theconditions of the first phase in order to meet the conditions prescribedfor full implantation.

The fastener applier 38 can implement this feature in various structuralembodiments. In the illustrative embodiment shown in FIG. 16A(1), thecarrier 128, coupled to a driver 52, includes a slot 130, which receivesthe L-shaped leg 66 to couple the fastener 28 for rotation with thecarrier 128. In this embodiment, the turns of the coil 54 rest iscomplementary internal grooves 132 that surround the carrier 128. Thegrooves 132 could be positioned along the entire length of the fastener28 or within a portion of its length. Activation of the drive mechanismrotates, as a unit, the driver 52, the carrier 128, and the helicalfastener 28 (as FIG. 16A(2) shows). This rotation causes the helicalfastener 28 to travel within the internal grooves 132 of the fastenerapplier and into the prosthesis 10 and tissue wall. Uninterruptedrotation of the carrier 128 will cause the helical fastener 28 to berotates completely off the carrier and through the prosthesis 10 andinto the tissue wall (as FIG. 16C shows).

In the illustrated embodiment, the drive mechanism includes a motorcontrol unit 134 (see FIGS. 16A(2), and 16B, and 16D). The motor controlunit 134 is conditioned to operate the carrier 128 in the two distinctphases, as above described. The first phase of fastener implantation isinitiated by the physician activating a rotation command, e.g., bymanipulating a first switch 136 on the handle 62. During the first phaseof deployment (FIG. 16B), the carrier 128 is driven sufficient to rotatethe helical fastener 28 to a position in which the distal portion of thefastener 28 has implanted itself into the target tissue, but in whichthe proximal portion of the fastener 28 is still retained within theinternal threads 132 of the carrier 128. At this point, the first phaseends, and the motor control unit 134 enters the lull phase,automatically interrupting rotation of the carrier 128. The motorcontrol unit 134 can accomplish motor control in this fashion by eitherconventional mechanical and or electronic means, e.g., through aprogrammable microprocessor.

At this juncture, the physician has the option of reversing theinsertion process and removing the fastener 28, if desired (see FIG.16D), e.g., by reversing the switch 136 or activating another switch 138on the handle 62. At this juncture, the physician also has the option ofcompleting the implantation process, e.g., by manipulating the switch136 in a preprogrammed fashion (for example, by double switching).

In one variation, the motor control unit 136 can receive inputreflecting a performance criteria measure during the first phase ofdeployment. The motor control unit 136 assesses the value of theperformance criteria, to determine whether it falls within apredetermined acceptable range. If so, the second phase of deploymentmay occur automatically without a pause and without a second input fromthe user. For example, motor current used during the first phase offastener deployment could be measured, and from this the fastenerdriving torque can be calculated. A torque within a range of acceptablevalues would imply that the fastener 28 has successfully entered thetarget tissue and fastener implantation could be completedautomatically. A torque that was outside the acceptable range couldresult in either a pause at the end of phase one, where the user couldmake the decision to continue or reverse the fastener deployment, or anautomatic reversal of fastener deployment.

In an alternative embodiment, a fastener release mechanism 114 of thetype shown, e.g., in FIGS. 13A/B and 14A/B can be used in associationwith a motor control unit 134. In this arrangement, the motor controlunit 134 is conditioned to operate the carrier 104 to drive the fastenerassembly 102 in a single phase of deployment into tissue. At this point,the release mechanism 114 can be operated in the manner previouslydescribed, to separate the fastener assembly 102 from the carrier 104.The motor control unit 134 can be conditioned by mechanical and/orelectronic means to indicate and/or control the number of revolutionsand/or control the number of revolutions and/or the torque applied toaccomplish the installation of the fastener assembly 102 in tissue. Inthis embodiment, there is no need for multiple phase, because thephysician ultimately controls the release of the fastener assembly 102by manipulation of the release mechanism 114.

Carriers with Tethered Fasteners

In all of the above embodiments, or as an alternative embodiment in andof itself, a fastener applier 38 can include an element 140 toreleasably tether a fastener 28 to the applier 38 even after thefastener 28 has been separated from the applier 38 (see FIG. 17A). Thetether element 140 serves as a “life line,” maintaining a connection oflast resort between the applier 38 and a fastener 28. The tether element28 allows the fastener 28 to be retrieved if, for any reason, thefastener 28 inadvertently breaks loose from tissue and/or the applier 38during or after implantation. The connection between the tether element140 and the applier 38 requires a deliberate act of the physician to bebroken, adding a confirming, a final step to the implantation process(see FIG. 17B).

The tether element 140 can be variously constructed. In FIG. 17A, thetether element 140 comprises a thread, braid, wire, or tubing structure142. The proximal end of the tether element structure 142 is attached tothe fastener applier 38 in a manner that can be detached by applicationof a deliberate pulling force. The distal end of the tether elementstructure 142 is frangible and can be broken by a force less than thedeliberate pulling force once desired deployment of the fastener 28 isconfirmed, as FIG. 17B shows. The tether element structure 142 hassufficient length to be able to retract the fastener applier 38 enoughto visualize the fastener in position (as FIG. 17A shows). The force tobreak the frangible distal end of the tether element structure 142 isless than the force required to dislodge the fastener 28 from tissue.Desirably, the frangible distal end of the tether element structure 142detaches from the fastener 28 without leaving remnants on the fastener28 (as FIG. 17B shows).

The tether element structure 142 can be sized and configured in other,different ways to form a frangible connection with a fastener 28. Forexample (see FIGS. 18A and 18B), the L-shaped leg 66 could be crimped toform an area of weakness 144 (FIG. 18A), to which the tether elementstructure 142 applies force to free the tether element structure 142from the fastener 28 (FIG. 18B).

Alternatively, the junction between the tether element structure 142 andthe fastener 28 can comprise an area of weakness 146 (e.g., be welding,soldering, gluing, heating, or shearing) that is broken by theapplication of a prescribed force in a prescribed manner, e.g., byrotation (FIG. 19A) or pulling (FIG. 19B). Alternatively, the junctionbetween the tether element structure 142 and the fastener 28 maycomprise a threaded joint 146 (see FIGS. 20A and 20B), or a snap-fitball and socket joint 148 (see FIGS. 21A and 21B), or slide-fit joint150 (see FIGS. 22 A and 22B; or a knotted joint 152 (FIGS. 23A and 23B);or a frictional junction 154 that is relieved by split open a tube 156using a rip cord 158 (FIGS. 24A and 24B). Still, alternatively, thejunction between the tether element 140 and the fastener 28 can comprisean interlocking mechanism 160, for example, a slidable outer sleeve 162that, when advanced (FIG. 25A), captures an appendage 164 on thefastener 28 and, when retracted (FIG. 25B), frees the appendage 164.

The preferred embodiments of the invention are described above in detailfor the purpose of setting forth a complete disclosure and for the sakeof explanation and clarity. Those skilled in the art will envision othermodifications within the scope and sprit of the present disclosure.

The above described embodiments of this invention are merely descriptiveof its principles and are not to be limited. The scope of this inventioninstead shall be determined from the scope of the following claims,including their equivalents.

We claim:
 1. A tool for applying an implantation force to a fastenersized and configured for implantation in tissue in response to animplantation force applied according to prescribed conditions, the toolcomprising: a tool body; a driven member carried by the tool body andbeing operable to apply the implantation force; a mechanism on thedriven member to couple the fastener to the driven member to transferthe implantation force from the driven member to the fastener; and acontroller coupled to the driven member, the controller including: aninitial phase operating the driven member to apply the implantationforce under conditions than are short of the prescribed conditions; alull phase commencing at the end of the initial phase interruptingoperation of the driven member; a final phase operating the drivenmember under conditions that supplement the conditions of the initialphase to achieve the prescribed conditions, the controller requiring,after the initial phase, a prescribed command to advance from the lullphase to the final phase; wherein the prescribed conditions are aprescribed time period or a prescribed number of rotations.
 2. The toolof claim 1, wherein the prescribed command is based, at least in part,upon input from an operator.
 3. The tool of claim 1, wherein theprescribed command is based, at least in part, upon input reflecting asensed operating condition.
 4. The tool of claim 1, wherein: the drivenmember is operable to apply a removal force to withdraw the fastenerfrom tissue; and the controller includes a removal phase operating thedriven member to apply the removal force, the controller requiring,after the initial phase, a different prescribed command to advance fromthe lull phase to the removal phase.
 5. The tool of claim 4, wherein thedriven member is rotated in one direction to apply the implantationforce and rotated in an opposite direction to apply the removal force.6. The tool of claim 1, further comprising an element configured totether the fastener to the tool body, the element comprising a frangibleportion.
 7. The tool of claim 1, wherein the driven member is rotated toapply the implantation force.
 8. The tool of claim 1, wherein the toolbody comprises a tubular member that carries the driven member and themechanism.
 9. The tool of claim 1, wherein: the tool body comprisesinternal threads and the fastener comprises a helical fastener; and aproximal portion of the helical fastener is retained within the internalthreads at the end of the initial phase.
 10. The tool of claim 1,wherein the mechanism comprises a distal portion having a configurationthat corresponds to a configuration of a proximal end of the fastener,such that the proximal end of the fastener engages with the distalportion of the mechanism to couple the fastener to the mechanismthroughout the initial phase.
 11. The tool of claim 10, wherein theproximal end of the fastener comprises a leg portion that engages withthe distal portion of the mechanism throughout the initial phase. 12.The tool of claim 1, wherein the fastener comprises a helical fastener.